/* 隐藏弹窗 */
#popup {
    display: none;
}

/* 显示弹窗 */
#popup:target {
    display: block;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 300px;
    padding: 20px;
    background-color: #fff;
    border: 1px solid #ccc;
}
